The present invention relates to a stencil printing machine having a cylindrical printing drum and, more particularly, to a construction for preventing ink leakage at the rear end part of the printing drum.
There have been proposed various constructions for prevention of ink leakage in stencil printing machine. For example, the present applicant proposes in Japanese Patent Application No. Sho 55-126933 the prevention of ink leakage at the rear end part in the direction of rotation of an ink-pervious area of a printing drum. According to this invention, an ink dam element is provided along the axial line of the printing drum at the rear end part in the direction of rotation of the ink-pervious area of the printing drum, whereby excessive ink carried backward by the rotation of the drum without being used for printing is held to be fed back into the printing drum.
However, there is such a problem that when there remains too much surplus ink not used for printing due to a small printing area of a perforated image on a stencil sheet, the surplus ink flows out over the ink dam element in the case of the structure provided with the ink dam element previously proposed. The ink flowing out over the rear end of the ink-pervious area will smear the printing paper and the stencil printing machine as well.